The present invention relates generally to a master friction clutch for a vehicle drive-train system and more particularly to a centrifugal master friction clutch having means for installing the clutch in a vehicle drive-train system.
Vehicle drive-train systems that include an internal combustion engine, a master friction clutch and a transmission are known in the art. Master friction clutches generally include a cover assembly having a pressure plate, a cover and a diaphragm spring, all coupled for rotation together with an engine flywheel. A typical master friction clutch also includes at least one friction plate, commonly called a driven disc, having at its outer periphery friction pads and at its inner periphery a hub that is mounted on a driven member, such as a transmission input shaft. When the clutch is disengaged, the pressure plate is axially removed from the friction plate and no torque is transferred between the engine flywheel and the friction plate. When the clutch is engaged, the pressure plate applies a clamping force against the friction plate causing the engine flywheel and friction plate to contact and transfer torque therebetween.
Normally closed (engaged) clutches generally include a release member, such as a bearing mechanism, to selectively disengage the clutch under direction of the vehicle operator. An exemplary procedure for installing a normally closed clutch in a vehicle drive-train system includes: (i) installing the friction plate(s) on a temporary installation shaft; (ii) securing the clutch cover assembly to the flywheel to clamp the friction plate(s) between the flywheel and a pressure plate; and (iii) removing the installation shaft to permit insertion of a transmission input shaft. The friction plate(s) are held in position after removal of the installation shaft by the clamping force of the pressure plate until the transmission can be installed into the vehicle drive-train system.
Normally open (disengaged) clutches, such as centrifugally operated friction clutches, are also known in the art. Centrifugally operated clutches generally include an input member driven by an internal combustion engine and weights pivotable with respect to the input member which, upon rotation of the input member, will rotate or pivot radially outward under the effect of centrifugal force to cause the input member to frictionally engage an output member. Unlike a normally closed (engaged) clutch, the pressure plate in a normally open (disengaged) clutch does not exert a clamping force on the friction plate(s) until the clutch is engaged. Thus, securing the clutch cover assembly of a normally open (disengaged) clutch to the engine flywheel does not necessarily clamp the friction plate(s) between the flywheel and the pressure plate.
An installation device for use in a normally open (disengaged) clutch has been developed, the details of which are disclosed in pending U.S. patent application Ser. No. 09/943,497, filed Aug. 30, 2001 and published as U.S. 2003-0042108-A1, which is owned by the assignee of the present invention and is incorporated by reference in its entirety. While the noted installation device has improved installation of a normally open (disengaged) clutch into a vehicle drive-train system, designers continue to improve upon the design to facilitate assembly of the installation device into the clutch assembly.
An installation device for a centrifugal clutch is disclosed. In an embodiment of the invention, the centrifugal clutch includes a clutch cover, a pressure plate for applying a clamping force against a friction plate, and at least one flyweight that moves radially outward under the effects of centrifugal force to cause the pressure plate to exert a clamping force against the friction plate. The installation device includes an installation hub moveable relative to the clutch cover between a first position, wherein the installation hub is engaged with the flyweight to force the engaged flyweight to move radially outward, and a second position, wherein the installation hub is disengaged from the flyweight. A resilient member biases the installation hub toward the second position and is selectively engaged with the clutch cover to inhibit movement of the installation hub toward the first position.